"These two are charged in addition to the first two already in custody," said Troy Police Captain John Cooney, referring to Keith Furgeson, 17, and Ahziarh Carter, 16, who were arrested earlier Tuesday.

"We still believe robbery to be the motive in the case and the investigation is still ongoing and active."

Records show Dunbar was arrested at Building 19 of Corliss Park, the scene of Monday's fatal stabbing.

Both Mallard and Dunbar were arraigned in Troy City Court Wednesday morning and are being held without bail in Rensselaer County Jail.

Deputy Police Chief Richard McAvoy said police responding to the scene at Building 19 of the Corliss Park Apartments discovered a "gruesome scene."

EMTs worked to save Smith, who had suffered "several" stab wounds to his torso, and rushed him to St. Mary's Hospital where he later died.

The latest arrests came after police reviewed surveillance footage from cameras installed by the Troy Housing Authority, which McAvoy said contained evidence police used to arrest Furgeson and Carter on Tuesday.

Smith's relatives told reporters he'd been enrolled as a student at Bryant and Stratton College in Albany, and had recently received a financial settlement that police believe was the motive for the robbery turned murder. Police also believe Smith was visiting an infant at one of the apartments at Corliss Park. McAvoy said the infant was present at the scene, but was not hurt in the attack.

Sources with knowledge of the investigation say police are looking into whether Smith may have been lured to the location in order to be robbed, though officials have not commented except to say the investigation is ongoing.